隨筆檔案(496)

//轉載請注明出處：http://hi.baidu.com/jadmin/blog/item/163ed2f8a8e88b0dd8f9fd46.html
/**
* @(#)MatrixMultiply.java
*
*
* @author JAdmin
* @version 1.00 2007/8/21
*/

import java.util.Scanner;

public class MatrixMultiply
{
public static void main(String[] args)
{
??? int m,n,p;
??? System.out.println("請輸入3個矩陣參數m,n,p.示例a[m][n]*b[n][p]=c[m][p]");
??? Scanner sr = new Scanner(System.in);
??? System.out.print("m=");
??? m = sr.nextInt();
??? System.out.print("n=");
??? n = sr.nextInt();
??? System.out.print("p=");
??? p = sr.nextInt();

??? int[][] a = new int[m][n];
??? int[][] b = new int[n][p];
??? int[][] c = new int[m][p];

??? System.out.println("請輸入數組a[" + m + "][" + n + "]");
??? input(a);
??? System.out.println("請輸入數組b[" + n + "][" + p + "]");
??? input(b);

??? //以下開始計算c[][]
??? for(int i = 0;i < c.length;i++)
???? for(int j = 0;j < c[0].length;j++)
????? c[i][j] = getMultiItem(a,b,i,j);

??? System.out.println("************The matrix a[][]************");
??? display(a);
??? System.out.println("************The matrix b[][]************");
??? display(b);
??? System.out.println("************The matrix c[][]************");
??? display(c);
}

private static void input(int[][] arr)
{
??? Scanner sr = new Scanner(System.in);
??? for(int i = 0;i < arr.length;i++)
???? for(int j = 0;j < arr[0].length;j++)
?????? arr[i][j] = sr.nextInt();
}

private static void display(int[][] arr)
{
??? for(int i = 0;i < arr.length;i++)
??? {
???? for(int j = 0;j < arr[0].length;j++)
????? System.out.print(arr[i][j]+" ");
???? System.out.println();
??? }
}

private static int getMultiItem(int[][] a,int[][] b,int p,int q)
{
??? //計算元素c[p][q]
??? int tmp = 0;

??? for(int i = 0;i < a[0].length;i++)
???? tmp += a[p][i]*b[i][q];
??? return tmp;
}
}